The documents listed below are incorporated herein by reference:                1. IEEE 802.15.4g, Part 15.4: Low-Rate Wireless Personal Area Networks (LR-WPANs) Amendment 3: Physical Layer (PHY) Specifications for Low-Data-Rate, Wireless, Smart Metering Utility Networks;        2. IEEE 802.11ah: Advantages in Standards and Further Challenges for Sub 1 GHz Wi-Fi, Stefan Aust, IEEE ICC 2012;        3. Part 15.4: Low-Rate Wireless Personal Area Networks (LR-WPANs), IEEE 802.15.4 e-2012; and        4. Field Area Network Working Group Field Area Network Technical Profile Specification, WI-SUN FAN.        
Wireless communication standards are intended to provide a framework for realizing effective wireless communication networks. Although such standards specify many details important for effective operation, they do not necessarily mandate any particular physical layer (PHY) modulation scheme. This allows for the use of various different modulation schemes. Thus, any given wireless communication device operating in a network may support one or more PHY modulation schemes. As an illustrative example, IEEE STD 802.15.4g identifies the following three modulations available for use in the network: frequency shift keying (FSK); orthogonal frequency division multiplexing (OFDM); and direct sequence spread spectrum (DSSS).
In networks compliant with IEEE STD 802.15.4g, a conventional PHY transmit frame is composed of a header portion that includes a preamble, and a payload portion that follows the header. For multiple available modulation schemes, each type of modulation has its own associated header, and the preamble carries information that enables proper reception of the entire frame. Consider now a conventional wireless communication device configured to detect frames having a specific modulation type. That is, for each frame, the receiver looks for and decodes only the header type associated with the modulation type that the receiver is currently using. Solutions are needed for effective communication among devices in a single network (e.g., IEEE 802.15.4g compliant network or other sub 1 GHz network) that use different modulations.
Continuing with the IEEE 802.15.4g example, that standard provides for interoperability among wireless communication devices by specifying FSK as a default modulation for the PHY header. Information in the FSK-modulated header identifies the modulation used for transmission of the payload that follows. The present work recognizes a disadvantage of the default FSK header. Note first that FSK, OFDM and DSSS have respectively different sensitivities, and thus correspondingly different ranges (distances) over which communication can be carried out. The range for DSSS is greater than for OFDM, and the range for OFDM is greater than for FSK. The shorter range FSK preamble limits effective communication ranges within the network. This can be seen by recognizing that any device that supports relatively lower modulations (e.g., OFDM or DSSS), but is too distant to detect the FSK preamble, will be prevented from realizing the longer communication ranges associated with the lower modulations it supports.
Another possible solution is to use the lowest of the multiple available modulations as the default modulation. However, the time duration of a header modulated with the lowest modulation would significantly degrade throughput. Thus, a relatively higher default modulation limits range, and a relatively lower default modulation limits throughput.